Surgical instrument



Oct. 7, 1958 M. MORRISON SURGICAL INSTRUMENT 5 Sheets-Sheet 1 Filed Feb.18, 1957 INVENTOR. M/lfSf/AA MOfP/SO/V ZVW/ M. MORRISON 2,854,981

3 Sheets-Sheet 2 INVEN TOR. MARSHAL MORE/SON BY WWMIMW%W ATTOENZPSURGICAL INSTRUMENT h mm Oct. 7, 1958 Filed Feb. 18, 1957 m fifi W 1 r mm T L\ I g T A +1 2 mm 2 mum 2 mm mm wm NM M. MORRISON SURGICALINSTRUMENT Oct. 7, 1958 I5 Sheets-Sheet 3 Filed Feb. 18, 1957 INVENTOR.MAPS/6M1 MUEP/SO/V BY United States Patent SURGICAL 1N STRUMENT MarshalMorrison, Plainwell, Mich., assignor t Orthopedrc Frame Company,Kalamazoo, Mich., a corporatron of Michigan Application February 18,1957, Serial No. 640,819

6 Claims. (Cl. 128-317) This invention relates in general to a surgicalcutting implement, which can be used in very confined zones and, moreparticularly, to a type thereof having an arcuate cutting edge, which isoscillated about the axis of the arc of said edge.

In spite of many advances in surgical techniques, particularly in thefield of bone surgery, there has long existed a pressing need for moreeffective and efiicient instruments for carrying out surgical operationsfor which the theoretical procedures have been well known. For example,it has long been recognized that the incision required for positioning abone cutting instrument is often much larger than the actual cut made inthe bone structure. This is usually due to the fact that the bonecutting instruments are relatively large and, furthermore, if theincision is too small, the'cutting edge may injure the soft tissue. Theonly instrument, with which I am familiar, which has attempted to meetthis problem, is the surgical saw shown in Patent No. 2,702,550, whichis assigned to the assignee of this application. However, this surgicalsaw was designed for use on the relatively soft bone structure in thenasal passages of a human being and is not suited for the relativelysustained and continuous use required in heavier work, as on harder andlarger bones in other parts of the anatomy. It has been found thatexcessive heat is developed between the frictional engagement of themoving parts of this instru ment, where it is used for extended periodsof time or on bone structure which is highly resistant to cutting.Because of the friction, and the heat resulting therefrom, the speed ofoscillation of the saw blade is also considerably limited. H-owever, itis known that a higher rate of blade oscillation, than is presentlypossible with an instrument such as that shown in said patent, is highlydesirable, particularly where relatively hard bone material is beingcut.

It is also important that the stroke of the cutting blade at a pointalong the cutting edge thereof be less than approximately /a inch, inorder to avoid injury to the tissues surrounding the bone, which isbeing cut.

Accordingly, a principal object of this invention has been the provisionof a surgical saw, especially designed for Working on relatively hard,bony material of the human body, which is located in regions which aredifiicult to reach or wherein the space for conducting the operation islimited.

A further object of this invention i the provision of a surgical saw, asaforesaid, by the use of which the incision required for reaching thebone to be cut can be substantially smaller than previously necessary toaccommodate existing saws for the same, or similar purposes.

A further object of this invention has been the provision of a surgicalsaw, as aforesaid, wherein the cutting edge of the saw is located at theend of a projection, or beam, having a relatively small cross-section,wherein an oscillatory movement of the cutting edge on said saw iseffected by means extending through said projection,

Patented Oct. 7, 1958 developed by means such as an electric motor, intosaid oscillatory movement of the saw edge with an absolute minimum offrictional losses, hence, with an absolute minimum of heat generation.

A further object of this invention has been the provision of a surgicalsaw, as aforesaid, which can be operated with a. minimum of effort, andthe cutting blade of which can be easily and quickly removed, as forcleaning, and then returned or replaced for operation without concernfor sensitive adjustments or critical areas which might otherwise reducethe effectiveness of the instrument.

Other objects and purposes of the invention will become apparent topersons familiar with this type of equipment upon reading the followingspecification and examining the accompanying drawings, in which:

Figure 1 is a side elevational view of a sagittal plane, surgical sawcharacterizing the invention.

Figure 2 is a partially elevational view and partially centrallycross-sectional view of a fragment of Figure 1, about as indicated bythe cutting line II-Il.

Figure 3 is a sectional view taken along the line III-III of Figure 2.

Figure 4 is a sectional view taken along the line IV-IV of Figure 1.

Figure 5 is a sectional view taken along the line VV of Figure 1.

Figure 6 is an exploded, broken View, partially in centralcross'section, of the drive shaft of said saw.

Figure 7 is a sectional view taken along the line VII- VII of Figure 6.

Figure 8 is a sectional view taken along the line VIII- VIII of Figure2.

Figure 9 is a sectional view taken along the line IX- IX of Figure 1.

Figure 10 is an end elevational view of the structure shown in Figure 3,as indicated by the cutting line at XX.

Figure 11 is a sectional view taken along the line XI XI of Figure 1.

Figure 12 is a sectional view taken along the line XII-- XII of Figure1.

General description In order to meet the objects and purposes set forthabove, there has been provided a sagittal plane, surgical saw comprisedof a hollow handle, in which a drive shaft is rotatably supported, andfrom one end of which there projects a blade-supporting beam, thelengthwise axis of said beam being a substantial extension of therotational axis of said drive shaft. The saw blade is pivotallysupported upon the free end of the beam, which slidably supports a pairof thrust rods, operable by said drive shaft, for effecting oscillatorymovement of said saw blade and wherein said surgical saw'convertsrotational motion,

about an axis transverse of said beam in response to rotational movementof said drive shaft.

For the purpose of convenience in description, the terms inner, outer,and derivatives thereof, will have reference to the geometric center ofthe surgical saw, and parts thereof. The terms front, rear, and derivatives thereof, will have reference, respectively, to the left and rightends of said surgical saw and parts thereof, as appearing in Figures 1to 5.

Detailed construction As shown in Figure 1, the surgical saw 10, towhich this invention relates, has an elongated, manually engageable body11 and an elongated beam 12, one end of which is removably supportedupon the front end of said body 11 and the other end of which removablysupports a cutting blade 13. The body 11, which is preferablycylindrical and fabricated from a durable material, such as stainlesssteel, has a co-axial bore 14 (Figure extending completely therethrough,The front and rear portions 15 and 16, respectively, of the bore 14 areenlarged and internally threaded adjacent to their respective outerends. Bearings 17 and 18 are disposed within the enlarged portions 15and 16 at the inner ends thereof, for the purpose of rotatablysupporting a drive shaft 19.

The enlarged portion 15 '(Figure 5) includes a cylindrical chamber 22between the threaded, front end 23 and the bearing 17. Amotion-converting device 24 (Figures 2, 5 and 6) is disposed within thechamber 22. The device 24 includes a head 25 which has a circularcrosssection of substantially greater diameter than the shaft 19 andwhich is co-axially secured to the front end of said shaft 19 within thechamber 22. The head 25 is provided with a substantially circular andplanar, front end surface 26, which is disposed at a relatively small,acute angle with respect to a plane perpendicular to the rotational axisofrthe shaft 19. In one particular embodiment, this angle isapproximately 4 degrees (Figure 6) and the centerline distance betweenthe rods 61 and 62 (Figure 9), which are described in detailhereinafter, is about /8 inch. A thrust bearing 27 is disposed withinthe chamber 22 between the head 25 and the radial hearing 17. Acylindrical sleeve 29, having a transverse partition 30 between the endsthereof, is mounted upon the front end of said head 25 so that saidpartition is snugly adjacent to the surface 26. A radial bearing 28 ismounted within the sleeve 29 on the side of said partition opposite saidhead 25, so that the axis of said bearing 28 is substantiallyperpendicular to, and co-axial with, said end surface 26.

A circular cam plate 32 is provided with an integral stub shaft 33,which is supported within the radial bearing 28. Said cam plate 32 has asubstantially planar cam surface 34 on the front side thereof which ispreferably parallel with the end surface 26 and, therefore, atsubstantially the same angle with the axis of shaft 19. Thus, as theshaft 19 is rotated, the axis of the stub shaft 33 will sweep through aconical path and the cam plate 32 will wobble with respect to said driveshaft, said cam surface 34 continuously remaining at the same angle withrespect to the axis of said shaft.

A connecting sleeve 37 (Figure 4), having a co-axial bore 38, isprovided with an externally threaded end portion 39, which is threadedlyreceived into the rear end portion 16 of the body 11. The adjacent, orrear, end of the drive shaft 19, which extends co-axially into the bore38, has a slotted, co-axial recess 42 (Figures 4, 6 and 7) for slidable,but non-rotatable, reception of the drive end 43 (Figure 4) of aflexible cable 44, the other end of which is connected in any suitablemanner to a prime mover 45 (Figure 1). The cable 44 is rotatablysupported adjacent to its drive end 43 within a connecting member 46,which member is removably held with respect to the connecting sleeve 37by means of the coupling device 47 (Figures 4 and 12). A set screw 48 isthreadedly received through a radially disposed, setscrew opening 49,which communicates with the rear end portion 16 of the bore 14 in thebody 11. Said screw 48 engages the end portion 39 of the connectingsleeve 37, whereby the sleeve 37 is held against rotation with respectto said body 11.

The beam 12 is comprised, in this particular embodiment, of a pair ofsubstantially identical metal tubes 50 and 51 (Figures 1 and 3), whichare secured, as by brazing, to diametrically opposite sides of, andsubstantially parallel with, the support rod 52. The tubes 50 and 51 androd 52 extend through, and are rigidly supported at corresponding endsof each within, and upon, the externally threaded plug 53 (Figures 2 and9), which is threadedly receivable into the front end portion 15 of thebore 14 in the body 11. A set screw 56 is threadedly received through aradially disposed, set screw opening 57, which communicates with thefront end portion 15 .4 of the bore 14 in the body 11. Said screw 56engages the peripheral surface 58 0f the plug 53 to hold same againstrotation in a substantially conventional manner. The front ends of thetubes 50 and 51 and the support rod 52 extend through, and are supportedupon, the base 59 of the bifurcated blade support head 60.

A pair of thrust rods 61 and 62 (Figure 3) are axially and slidablydisposed within the tubes 50 and 51, respectively, and are slightlyshorter than their respective tubes. Two pairs of bearing balls 63, 64,65 and 66 (Figure 3) are disposed at opposite ends, respectively, of thethrust rods 61 and 62 and extend partially into the tubes 50 and 51.Said bearing balls, which are preferably of substantially the samediameter as the inside diameter of the tubes with which they areassociated, are held snugly against the ends of said thrust rods bymeans of the bearing ball retainers 67 and 68. The bearing ball retainer68, located at the rear, or body, end of the beam 12 (Figures 3 and 10)is comprised of a circular plate 71 having a central portion which isoff-set to provide a recess 72, and having a co-axial screw opening 73.A retainer screw 74 is slidably received through said opening 73 andthreadedly received into the threaded screw opening 75 in the rear endof the support rod 52. The head 76 of said screw 74 is disposed in therecess 72 for pivotally and rotatably supporting the plate 71 withrespect to the rear end of the beam 12, and against the bearing balls 64and 66.

The rear surface of the plate 71 (Figures 2 and 5) on the retainer 68 issnugly, but slidably, engageable with the cam surface 34 on the camplate 32 when the threaded plug 53 on the beam 12 is threadedly disposedwithin the front end portion 15 of the bore 14.

The bearing ball retainer 67 (Figures 3, 8 and 11) is comprised of anelongated plate 77 which is disposed between the parallel arms 78 and 79of the blade support head 60. Said plate 77 has a centrally disposed,offset portion 82, through which an opening 83 is provided for slidablereception of a retainer screw 84. Said screw 84 is threadedly receivedinto an appropriate opening 85 in the adjacent end of the support rod 52for pivotally holding said plate 77 with respect thereto, and againstthe bearing balls 63 and 65. A set screw opening 87 (Figure 11) isprovided through the blade support base 59 and the adjacent portion ofthe rod 52, and communicates with the retainer screw opening 83. A setscrew 86 is threadedly received into the opening 87 for engaging andholding the retainer screw in a selected position. Accordingly, byproper adjustment of the screws 76, 84 and 86, the bearing ballretainers 67 and 68 will cooperate to prevent dislodgement of theirrespective bearing balls from their positions adjacent to the ends ofthe thrust rods 61 and 62, while permitting said thrust rods toreciprocate simultaneously with respect to the beam 12 and in opposite,axial directions with respect to each other.

The blade support 60 is provided with a pivot shaft 90, which slidablyextends through the shaft openings 91 and 92 (Figure 11) in the supportarms 78 and 79, respectively. Said shaft is rotatably supported at oneend upon, and held in place by, the front end of the flexible member 93,the rear end of which is secured, as by means of the screw 94 (Figures 1and 2) upon the beam 12 at a point spaced substantially from the bladesupport 60. Thus, by bending the member 93 away from the beam 12, thepivot shaft 90 can be moved out of its position extending through thearms 78 and 79.

The blade 13 (Figures 1 and 2) is provided with a hub member 95, havinga shaft opening 96, through which the pivot shaft 90 is slidablyreceivable for rotatably supporting said hub member. The blade 13 isprovided with a cutting edge 97 and said hub 95 is provided with a flatsurface 98 (Figures 3 and 11) along a chord line thereof, which is onthe diametrically opposite side of said hub 95 from the cutting edge 97of the blade 13, in this particular embodiment. The surface 98 isarranged with respect to the shaft opening 96 so that it will snugly,but slidably, engage the adjacent side of the elongated plate 77 whenthe blade 13 is supported upon the pivot shaft 90. It will be recognizedthat the chord surface 98 can be placed in a variety of positions aroundsaid hub 95 and with respect to said cutting edge 97, depending upon thedirection in which it is desired to have the cutting edge 97 extend fromthe end of the beam 12.

Operation Prior to operation of the surgical saw 10, the retainer screw84 (Figure 3) is tightened until the balls 63, 64, 65 and 66 are firmlyheld between said retainers 67 and 68 and the adjacent ends of the rods61 and 62. The retainer screw 84 is then locked in position by the setscrews 86 (Figure 11). A blade 13 (Figure 2) of the proper type ismounted upon the blade head 60, by moving the shaft 90 axiallysidewardly, placing said hub 95 between the support arms 78 and 79, andthen inserting the shaft 90 into the shaft opening 96 in the hub 95. Thethreaded plug 53 of the beam 12 is disposed within the threaded end 15of the body 11 and held there by the set screw 56, so that the plate 71of the bearing ball retainer 68 will snugly, but slidably, engage thecam surface 34 of the motion-converting device 24. The connecting member46 is inserted into the connecting sleeve 37 (Figure 4), so that thedrive end 43 of the flexible cable 44 is received into the slot 42 inthe adjacent end of the drive shaft 19, whereby rotation of the cable 44(Figure 1) by the prime mover 45 will effect a rotation of said driveshaft 19. The coupling device 47 releasably holds the connecting member46 within the connecting sleeve 37, thereby holding the drive end 43 ofsaid cable 44 in positive engagement with the drive shaft 19.

Accordingly, if the prime mover 45 is energized, the drive shaft 19 willbe rotated with respect to the body 11, thereby causing said cam plate32 to wobble with respect to the adjacent end of the beam 12. Due to theengagement between the cam surface 34 on the cam plate 32 and thebearing ball retainer 68, the wobbling of the cam plate 32 results in amovement of one of the bearing balls 64 and 66 toward the blade head 60during a half-revolution of said shaft 19, immediately followed by anurging of the other of said bearing balls 64 and 66 toward said bladehead 60 during the remaining half of a revolution of said drive shaft19. Due to the snug engagement between the bearing balls, thrust rodsand bearing ball retainers, as shown in Figure 3, movement of one of thethrust rods and its associated bearing balls in one direction will beautomatically accompanied by axial movement of the other of said thrustrods and its associated bearing balls in the opposite direction. Thus,the reciprocal movement of the bearing balls 64 and 66 is translated bythe thrust rods 61 and 62 and the bearing balls 63 and 65 into apivotal, oscillatory movement of the plate 77 of the bearing ballretainer 67 about its offset portion 82. In turn, pivotal movement ofsaid plate 77, which is snugly engaged by the chord surface 98 on thehub 95, is translated into a pivotal oscillation of the blade 13, henceof the cutting edge 97 thereof, about the axis of said hub 95.

As shown particularly in Figures 3 and 5, conversion of the rotarymotion of the pivot shaft 90 into the pivotal oscillation of the blade13 is accomplished with anti-friction, ball bearing engagement betweenvirtually all surfaces where friction would otherwise become a materialconsideration. The retainers 67 and 68 are held by the screws 84 and 74,sufficiently loosely with respect to the beam 12, that the retainerswill operate substantially independently of contact with said screws,except as said screws keep said retainers centered with respect to saidbeam.

Although a particular, preferred embodiment of the invention has beendescribed hereinabove for illustrative purposes, it will be understoodthat variations or modifications thereof, which lie within the scope ofthe invention, are fully contemplated unless specifically stated to thecontrary in the appended claims.

I claim:

1. A cutting instrument, comprising: a body having a drive shaftrotatably supported therein; a beam supported upon said body andextending therefrom along the extended rotational drive axis of saidshaft; a cutting blade pivotally supported upon the free end of saidbeam for movement about a blade axis transverse of said beam, said bladehaving a non-cutting driving edge which is spaced from said blade axisand arranged substantially transverse of said drive axis; a pair ofsubstantially parallel, thrust rods extending along said beam andsubstantially between the driving edge of said blade and the adjacentend of said drive shaft; a bevel plate rotatably supported upon theadjacent end of said drive shaft, and having a surface continuouslydisposed at a small angle to a plane perpendicular to the axis of saiddrive shaft: first anti-friction means snugly disposed between saidsurface and the adjacent ends of said thrust rods; and secondanti-friction means snugly disposed between said driving edge and theother ends of said thrust rods, whereby rotation of said drive shafteffects a wobbling of said surface, hence a reciprocation of said thrustrods and oscillation of said cutting blade.

2. A cutting instrument, comprising: a body having a drive shaftrotatably supported therein; a beam supported upon said body andprojecting therefrom along the extended rotational axis of said shaft; acutting blade pivotally supported upon the free end of said beam formovement about an axis transverse of said beam, said blade having anon-cutting edge spaced from its pivotal axis;

a pair of substantially parallel, thrust rods axially and slidablysupported with respect to said beam, said rods extending between, andbeing spaced slightly from, said edge and the adjacent end of said driveshaft; first antifriction means disposed between said thrust rods andsaid adjacent end of said shaft; means mounted upon said adjacent end ofsaid drive shaft and having a beveled surface snugly engageable withsaid first anti-friction means for effecting axial movement of saidthrust rods; second anti-friction means snugly disposed between saidthrust rods and said edge, for effecting oscillatory movement of saidblade in response to axial movement of said thrust rods, the first andsecond anti-friction means being arranged so that movement of one thrustrod in one axial direction is simultaneously accompanied by axialmovement of the other thrust rod in the opposite direction.

3. The structure of claim 2, wherein said first and second anti-frictionmeans both include bearing balls engaged with the ends of said thrustrods and bearing ball retainers pivotally supported upon said beam forholding said bearing balls snugly against said rods, one of saidretainers being engageable with said beveled surface and the other ofsaid retainers being engageable with said edge.

4. In a surgical instrument having a rotatable shaft, a cutting bladelying substantially in a plane including the axis of said shaft andmeans pivotally supporting said blade for oscillatory movement in saidplane around a blade axis, means for converting rotational movement ofsaid shaft into oscillatory movement of said blade, com prising: a pairof thrust rods extending substantially parallel with said shaft axisbetween said blade and one end of said shaft; means connected to saidblade supporting means and supporting said rods for axial movement; adevice, including anti-friction means, associated with said one end ofsaid shaft and the ends of said thrust rods adjacent to said shaft foreffecting intermittent, axial movement of said rods toward and away fromsaid blade; and means including anti-friction means being snuglydisposed between the other'ends of said thrust rods and said blade, forconverting the movement of said thrust rods into oscillatory motion ofsaid blade about said blade axis.

5. In a surgical instrument having a rotatable drive shaft, a cuttingblade spaced from said shaft and intersected by the extended axisthereof, and structure rotatably supporting said shaft and pivotallysupporting said blade, mechanism for converting rotation of said shaftinto oscillatory movement of said blade, comprising: a pair of parallelthrust rods substantially parallel with said axis and extendingsubstantially between said blade and the adjacent end of said shaft;housing means connected to said blade supporting structure andsupporting said rods for reciprocal movement; a bevel plate rotatablysupported upon said adjacent end of said shaft and having a surfaceconstantly inclined slightly to a plane perpendicular to said axis ofsaid shaft; a pair of bearing balls disposed at opposite ends of each ofsaid rods; and bearing ball retainers pivotally and rotatably supportedwith respect to said housing means for snugly holding said bearing ballsagainst said rods, one of said retainers being engageable with saidsurface and the other of said retainers being engageable with saidblade, whereby rotation of said shaft effects a reciprocation of saidrods and an oscillation of said blade.

6. In a surgical instrument having a rotatable shaft, a cutting blade,means pivotally supporting said blade for oscillatory movement about ablade axis, means for converting rotational movement of said shaft intooscillatory movement of said blade, comprising: a pair of thrust rodsextending substantially parallel with the axis of said shaft betweensaid blade and one end of said shaft; means connected to said bladesupporting means and supporting said rods for axial movement; a device,including anti-friction means, associated with said one end of saidshaft and the ends of said thrust rods adjacent to said shaft forelfecting intermittent, axial movement of said rods toward and away fromsaid blade; and means including anti-friction means, snugly disposedbetween the other ends of said thrust rods and said blade for convertingthe movement of said thrust rods into oscillatory motion of said bladeabout said blade axis.

References Cited in the file of this patent UNITED STATES PATENTS2,702,550 Rowe Feb. 22, 1955

